1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device which can improve the charging of pixel cells of the display device, and a method of driving the same.
2. Discussion of the Related Art
In general, a liquid crystal display device displays desired images by controlling light transmittance of liquid crystal cells in response to a video signal. Active-matrix type liquid crystal display devices are particularly well suited for displaying moving picture because a switching element is provided in each liquid crystal pixel cell. In an active-matrix type liquid crystal display device, a thin film transistor (hereinafter, referred to as a “TFT”) is used as the switching element.
A liquid crystal display device includes a plurality of gate and data lines that cross each other to thereby define the plurality of liquid crystal pixel cells. To prevent deterioration of the liquid crystal, the data voltages applied to each pixel cell alternate in polarity.
FIG. 1 is a waveform diagram illustrating the polarity of data applied to pixel cells in a dot-inversion driving method. As shown in FIG. 1, the polarity of data is inverted for each frame period, and the inverted polarity data is supplied to each data line. The data supplied to each pixel cell for a frame period is maintained by the pixel cell until data is supplied for the next frame to thereby display a picture image for one frame period.
As shown in FIG. 1, the polarity of data supplied to a pixel cell is inverted on a frame period basis. That is, the data applied to a pixel cell is inverted from the positive polarity to the negative polarity or from the negative polarity to the positive polarity every frame period.
However, when the polarity of data is inverted every frame period, the charging of pixel cells to target values for displaying an image deteriorates, thereby degrading the picture quality. For example, assuming that a pixel cell was supplied with data of positive polarity during a previous period, and is supplied with the data of negative polarity during the current period, it can be difficult to charge the pixel cell sufficiently rapidly to the reach the desired value represented by the data of negative polarity from the positive polarity data supplied to the pixel cell during the previous period.